Frying pan



Feb. 13, 1951 T. B. CHACE 2,541,034

FRYING PAN Filed Dec. 14, 1946 INVEN TOR.

iioM/v 5. (Inez- Patented Feb. 13, 1951 STATES PATENT OFF 1. Myinvention relates to frying pans of theatype using copper clad steel.

It= iswelliknownthat: the upper or: frying surface. of a. frying: panshould be, constructed of a: materialv having: a; higl-l degree of iresistance to:

the; corrosion. incident. to frying; operations" whereas the frying panas a whole: should? have; good thermalconductivity soaas uniformly to;dis

tribute the. heat applied; thereto and most cf, fectively to. transferthe heat: from; the under surface thereof to the substance being fried;It is: especially desirable that; good thermal: conductivity in. thelateral: direction across: the; pan. be provided: inasmuch: as the,applied, heat is: con--- centre-ted; along; the-:flame. or heatingelement of; the stova. One; material; having: these: charac;:-

teristics. is: copper clad; stainlessv steel. which has a. good thermal.conductivity byreason ofv the: copper-portion and-;a;.high. degree of;resistance to: corrosion by reason: of. thestainless; steel. pore tion.Typical, of: this: material is; the composite metal; stock; described.in my Patent; 2;:235,-200,- issued: March. I8, 19.41;, which.comprisesa; rela-- tively=thinlayer orchromiumferrite; alloy bonded: tearelatively; thick: layenofcopper. In addition this materiar is:vrelatively inexpensive. as. it can.

be manufactured; by: massv production. rolling operations: such as.those described in my Patent 2,325,659, issued August 3, 1943.

It is further"desirableina frying pan to construct; the; pan of g shapemost, effective1yto, utilize the total area of the stoveor other: unitused for frying. purposes. To this end, it is desirable that the pan beof approximately square shape rathenthan circular shape, therebycovering a:

square: area over thsburner andzpermitting maize imum utilization. ofthe stove: area.

I? have discovered that when. a. frying-pangis constructed. of, copperclad-s, stainless steel; and is shaped to approximatea square,difficultyisrcne countered due. to.-, the tendency of the pan to warpand bend under the rapid temperature variations and large amounts ofheat incident to frying operations. This" tendency is: due to theunequal thermal coefiicients of expansion of the metal layers, togetherwith the fact that the heat is not uniformly applied to the undersurface of the pan. For these reasons it has heretofore not beenpossible to provide a frying pan taking advantage of the benefits ofcopper clad stainless steel while at the same time approximatinga squareshape to take maximum advantage of the stove area.

It is an object of my invention to provide an improved frying pan ofapproximately square shape.

Another object of my invention is to provide an improved copper cladstainless steel frying pan approximating a square shape and having ahigh degree of resistance to warpingij observed that while the pan isgenerally of square" The novel features. which. I believe tobechareacteristic of my invention are set forth with. pare ticularlityin the appended claim. My invention itself, however, both as to itsorganizationand; method of operation, together with further. obejectsand advantages thereof, may best be understood" by reference to thefollowing: description taken inconnection. with the accompanyingdrawing:

Onthe-drawingi Figure l is a plan view showing a frying pain constructedin accordance'with the principles;cl: my invention; and

Figure 2' is a; cross section viewthrough the line II-II; Figure 1.

As shown on the drawing:

The frying pan consists of a flat frying por-- tion; designated as Iii.Figure l'. As shownin Figure 2; theupper or fryingsurface ofthe-fry-ting portion is of stainless steel; designated as: l2, whereas the lowerorheatin surface is off copper; designated by M. The pan has an opturned edge l-6 terminating in lip portion I8; on one edge of lipportion8-handle mounting member 20 is brazed, welded, or otherwise attached. Ths member includes threaded insert 22 having threads to coact with thethreaded end. of bolt- 24". Bolt 24 passes; through an openingiii-handle 2G; Handle; 26 also containsan edge portion 28 to enact inabutting relationship with handle; mounting member, 28 to secure arig-id attachment'; Handle 26 is preferably constructed of ebonite orsimilar material having a low coefllcient of: thermal conductivity to:the, end, that; it" is cool at all times and permitsliftingthe fryingpan w thout" discomfort.

While copper clad stainless steel, provides; a high degree of resistanceto corrosion on; the; stainless steel sideandgoodoverall'thermahconductivityby reason of the copper side; itis sub:-.jectto warpageand failure by reason of theiunv equal thermal expansionof the; steelias. compared to the copper and the unequalapplicaticnofrheat fromthestove; In. general, the steel tendsto expand less thanthe copper, in some instances unin frying pans of this material unlessthe dimensions of the pan are properly chosen relative to the thicknessof the metal.

I have discovered that a frying pan having a high degree of resistanceto warping can be made by utilizing the particular shape shown in thedrawing, together with copper clad stainless steel having a suitableproportion of copper. It will be shape it is in actuality a combinationof curved surfaces. The corners consist of arcs of radius 30 struckabout the corners of a square having each sideof length 32 whereas theedges are arcuate portions of circles having radius 36. Furthermore, theupturned edge I6 is turned with a definite radius 36, Figure 2.

The exact values of radii so, 34 and as, to

gether with the distance 32, may, of course, be varied over a reasonablerange without encountering an unreasonable tendency of the pan to.

warp. As an indication of the approximate values, the followingdimensions are typical:

From actual construction and tests I have discovered that a satisfactoryfrying pan can be made having the above dimensions. However, if thethickness of the copper portion 14 is reduced to, say, .032 inch and thetotal thickness offrying portion 16 correspondingly reduced 'to .037

inch, Warping has been found to take place.

1 am not now able to explain with precision the scientific phenomenaresponsible for the'successful operation of the above described fryingpan.

In general, however, I attribute this operation to the fact that at nopoint therein is there any very sharp bend and that the copper issufficientlythick to withstand the, tendency of the steel to pull withrespect thereto. In addition, the copper is of thickness to distributethe heat in a uniform manner over the surface of the pan despite theunequal application of heat thereto by the stove.

:It will of course be evident that the above dimensions are merelyrepresentative and indicate only to an approximate degree the dimensionsthat maybe used in a successful pan. In general, frying pans ofall sizesmay be constructed by proportioning the dimensions relative to thethickness of the material used. Thus, the dimensions of'the pan may bedescribed with reference to the. thickness of the base I0 as follows:

' Thickness of copper, approximately eight times Radius 30,approximately nineteen times the thickness of the frying portion.

Distance 32, approximately oneehundred forty times the total thicknessof the frying portion. Radius 34, approximately four-hundred eightytimes the thickness of the frying portion.

Irigeneral, frying pans of the above-described type can best beconstructed by stamping from sheets of copper clad steel. This operationlends itself to mass production with consequent economy of materials andlabor.

' While I have shown a particular embodiment of my invention, it will ofcourse be understood that I do not wish to be limited thereto since manymodifications and alternative constructions may be made withoutdeparting from the spirit and scope thereof. In particular, copper cladstainless steel made by processes other than rolling, as for exampleelectro-deposition, may

be used. I, of course, contemplate by th ap.-.

pended claim to cover any such modifications as fall within the truespirit and scope of my invention.

I claim as my invention: I In a fryin panfa single dished stampingblanked from sheet material of'uniforrn thickness comprising copper cladstainless steel, the sheet material comprising coextensive copper andstain-r less steel layers and with the copper being of a thicknesssubstantially greater than the stainless steel, said stamping being insubstantially square form and comprising a fiat bottom with the sideperimeter sections formed on large radius arcs to curve slightlyoutwardly and the corners curving outwardlyon smaller radius arcs, and acontinu ous upstanding marginal flange bounding said bottom and havinground corner walls and slight-,--

1y outwardly curved side walls between the corner wallsgenerallycomplementary to the bottom perimeter, the curved side wallsand curved corner Walls of the flange rigidirying the stamping andresisting warping of the metal layers in said pan bottom and the cornerportions of saidbottom providing radial heat distribution extensions ofthe bottom for distributing heat from the central portion of the panbottom'to the flange whereby the pan is substantially uniformly heated:and heat Warpage of the bottom avoided so that the bottom remains fiatat frying temperatures.

. THOMAS E. CHACE.

REFERENCES CITED- The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

